A liquid crystal display device has advantages such as thinness, lightweight, low power consumption and so on, and is widely used in various technical fields such as computers, word processors, television sets, mobile phones, handheld terminal devices and so on. In addition, so-called touch panels of such liquid crystal display devices having a mechanics of manipulation by touch on their screen are spreading rapidly. The touch panels are widely used in mobile phones like smart phones, tablet computers, handheld terminal devices, automated teller machines, automatic vending machines, personal digital assistances, copying machines, facsimiles, game machines, guiding devices set up in facilities such as museums and department stores, car navigation systems, multifunctional terminals set up in convenience stores or monitoring devices of railroad vehicles.
The touch panel generally has a transparent electroconductive laminate comprising a transparent substrate on which a transparent electrically conductive layer is formed.
A PET film or a polycarbonate film is commonly used as a substrate film of a transparent electroconductive laminate thanks to its high transparency and reasonable price.
A transparent hard coat layer can be preferably applied onto such a substrate film with a view to improving scratch resistance and durability.
A transparent electrically conducting layer of a transparent electroconductive laminate can be produced in use of a metal oxide such as indium tin oxide (ITO) by a processing such as a vacuum deposition method, a sputtering method, a chemical vapor deposition (CVD) method, an ion plating method, a spray method, to obtain a transparent electrically conducting layer on a substrate film.
In order to fit a multi-point input system which is mainly used in recent years, further patterning process is needed. On the other hand, there is a trouble of visual discrimination between an area having a transparent electrically conducting layer such as ITO and an area without the electrically conducting layer, which is caused by a pattering of the electrically conducting layer.The trouble provides largely visibility deterioration of a touch panel.
JP No. 2011-076932 A (Patent Document 1) describes a transparent conductive film in which a first transparent dielectric layer and a transparent conductive layer are formed on a transparent substrate in this order, wherein a pattern portion and a pattern opening portion are formed in the transparent conductive layer by patterning, and a relationship 0<=¦a*P−a*O¦<=4.00 is satisfied and a relationship 0<=¦b*P−b*O¦<=5.00 is satisfied where a hue a* value and a hue b* value of reflected light when the pattern portion is irradiated with white light are a*P and b*P, respectively, and a hue a* value and a hue b* value of reflected light when a portion directly under the pattern opening portion is irradiated with white light are a*O and b*O, respectively (claim 1).
In Patent Document 1, controlling of layer thicknesses and refraction indexes of the first transparent dielectric layer and the second transparent dielectric layer results in satisfaction of the above characteristics (claim 3, paragraph 0012 and the like).
JP No. 2011-076802 A (Patent Document 2) describes a transparent conductive film comprising a transparent substrate, a second transparent conductive layer, an insulating color difference adjusting layer and a first transparent conductive layer laminated in sequence, the second transparent conductive layer, the insulating color difference adjusting layer and the first transparent conductive layer being possibly formed on each side of the transparent substrate, in which the conductive face is formed as the upper face of a first transparent conductive layer by patterning the first transparent conductive layer, and the insulating face is formed as the upper face of the insulating color difference adjusting layer (claim 1). Patent Document 2 discloses that applying the second transparent conductive layer can reach a high transmittance and suppression of a difference between visibilities (paragraph 0014 and the like).